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Okay, forget O_EXCL, do lots of other obscure checks instead =)

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git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@381 35c25a1d-7b9e-4130-9fde-d3aeb78583b8
This commit is contained in:
Chris Allegretta 2000-12-04 05:15:39 +00:00
parent 908805a2e8
commit 07f9ee059f
2 changed files with 31 additions and 18 deletions
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4
ChangeLog
View File

@ -1,9 +1,9 @@
CVS code -
- files.c:
write_file()
- Added O_EXCL to open call if tmp is set, more security which hopefully
fixes any remaining security issues.
- Added tmp check to TMP_OPT section (how apropriate).
- Added new consistency checking code from securityfocus
article by Oliver Friedrichs.
- winio.c:
edit_add()
- Off by one display error (fix by Rocco Corsi).

45
files.c
View File

@ -301,8 +301,8 @@ int write_file(char *name, int tmp)
long size, lineswritten = 0;
char buf[PATH_MAX + 1];
filestruct *fileptr;
int fd, mask = 0, realexists;
struct stat st;
int fd, mask = 0, realexists, anyexists;
struct stat st, st2;
static char *realname = NULL;
if (!strcmp(name, "")) {
@ -327,24 +327,18 @@ int write_file(char *name, int tmp)
/* Check to see if the file is a regular file and FOLLOW_SYMLINKS is
set. If so then don't do the delete and recreate code which would
cause unexpected behavior */
lstat(realname, &st);
anyexists = lstat(realname, &st);
/* New case: if the file exists, just give up. Easy way out of
all security issues */
if (tmp && realexists != -1)
/* New case: if the file exists, just give up */
if (tmp && anyexists != -1)
return -1;
else if (ISSET(FOLLOW_SYMLINKS) || !S_ISLNK(st.st_mode)) {
/* If tmp is set, use O_EXCL, more security, YAY! */
if (tmp)
fd = open(realname, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
S_IWOTH);
else
fd = open(realname, O_WRONLY | O_CREAT | O_TRUNC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
S_IWOTH);
/* Open the file and truncate it. Trust the symlink. */
fd = open(realname, O_WRONLY | O_CREAT | O_TRUNC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
S_IWOTH);
/* First, just give up if we couldn't even open the file */
if (fd == -1) {
if (!tmp && ISSET(TEMP_OPT)) {
UNSET(TEMP_OPT);
@ -355,6 +349,25 @@ int write_file(char *name, int tmp)
free(realname);
return -1;
}
/* Now we fstat() the file, to make sure it's the same file still!
Thanks to Oliver Friedrichs(?) for this code from securityfocus */
if (fstat(fd, &st2) != 0) {
close(fd);
return -1;
}
/* Here we make sure the inode and device numbers are the
* same in the file we actually opened, compared to the file
* we performed the initial lstat() call on.
*/
if (st.st_ino != st2.st_ino || st.st_dev != st2.st_dev) {
close(fd);
return -1;
}
}
/* Don't follow symlink. Create new file. */
else {